The art is replete with devices of the type described above, U.S. Pat. Nos. 3,915,786, 3,954,550 and 4,238,269 being illustrative examples. Such devices are commonly used to seal rectangular boxes filled with merchandise moved past the device either manually or by a conveyor. Typically such devices include an application member such as a roller for supporting an end of the tape adhesive side out in a contact position at which the tape end will be contacted by a box. Upon such contact the tape end adheres to the box. Further movement of the box then pulls the tape from the device between the box and the application member while the device presses the tape against the contour of the box. Subsequently, severing means on the device sever the applied length of tape from the supply length of tape and means on the device engages the tape adjacent the newly severed end and moves it with the application member back to its contact position for contact by the next box moved past the device.
Typically the severing means includes a knife having a serrated edge mounted at one edge of the path for the boxes and is controlled so that after a predetermined length of tape being applied to the box has been pulled past the knife, the knife will move causing the points of the serrated edge to pierce through and sever the tape.
While such severing means works quite well when boxes are moved at a relatively slow and steady rate past the device, (as is normally the case when boxes are moved past the device by a conveyor) problems can arise when boxes are moved through the device at a relatively rapid rate, as will often occur when boxes are manually moved past the device. Under these circumstances, the tape is moving rapidly past the tips of the serrated knife which is essentially at a fixed position along the path of the tape as it cuts through the tape. Such rapid movement of the tape can break off the sharpened edge of the knife, particularly on the points along the serrated edge, causing the knife to become dull and resulting in uneven cut edges on the tape, or even failure to cut the tape. In extreme cases, blades which might last for six months when used to cut tape applied to boxes being moved by a conveyor at a relatively slow speed require changing every week to facilitate taping the same number of boxes per week manually moved rapidly past the device.